From 321e7ee3e21c30e07de28a5d07252017c4f4f96e Mon Sep 17 00:00:00 2001
From: Yaroslav Bolyukin <iam@lach.pw>
Date: Fri, 22 Apr 2022 18:51:05 +0000
Subject: [PATCH] fix: string index bounds check


---
--- a/crates/jrsonnet-evaluator/src/error.rs
+++ b/crates/jrsonnet-evaluator/src/error.rs
@@ -36,6 +36,8 @@
 
 	#[error("array out of bounds: {0} is not within [0,{1})")]
 	ArrayBoundsError(usize, usize),
+	#[error("string out of bounds: {0} is not within [0,{1})")]
+	StringBoundsError(usize, usize),
 
 	#[error("assert failed: {0}")]
 	AssertionFailed(IStr),
--- a/crates/jrsonnet-evaluator/src/evaluate/mod.rs
+++ b/crates/jrsonnet-evaluator/src/evaluate/mod.rs
@@ -589,13 +589,19 @@
 					n.value_type(),
 				)),
 
-				(Val::Str(s), Val::Num(n)) => Val::Str(
-					s.chars()
+				(Val::Str(s), Val::Num(n)) => Val::Str({
+					let v: IStr = s
+						.chars()
 						.skip(n as usize)
 						.take(1)
 						.collect::<String>()
-						.into(),
-				),
+						.into();
+					if v.is_empty() {
+						let size = s.chars().count();
+						throw!(StringBoundsError(n as usize, size))
+					}
+					v
+				}),
 				(Val::Str(_), n) => throw!(ValueIndexMustBeTypeGot(
 					ValType::Str,
 					ValType::Num,

-- 
gitstuff